Two weeks after a massive earthquake leveled much of this impoverished city, a wave of new infections and injuries has emerged, further taxing the nation’s shattered health care system.

Patients whose wounds were treated in the chaotic days following the quake are now returning with deep infections, the legacy of squalid conditions that make it impossible to keep open sores clean.

Rashes and gastrointestinal ailments, byproducts of the lack of clean water and sanitation, are becoming more common. And daily life on streets littered with rubble and marked by hopelessness is exacting a toll, as careering vehicles strike pedestrians and sprays of buckshot inflict wounds.

The shifting trajectory of suffering in Haiti is visible at a disaster field hospital staffed largely by medical workers from New England. Inside a taupe tent, an 18-year-old spiraled downward swiftly over the weekend.